As local communities consider safe injection sites for drug addicts, an eye-opening new study casts doubt on whether they really make a difference in the opioid crisis.

People can use drugs like heroin under medical supervision at those sites. The goal is to save lives and prevent the spread of disease.

RELATED: Seattle considers mobile safe injection van

KIRO7 was the first to show you Vancouver’s safe injection site called “InSite” in 2016. Every day, people line up outside and inject heroin on the street while waiting to get in.

Right now King County is working to figure out where to put two safe injection sites. But a new study puts into question whether they really save lives.

Research just published in the “International Journal of Drug Policy” says, “Medically supervised safe injection centers were found to have no effect on overdose mortality or syringe/equipment sharing.”

The study says, “There is a substantial body of research on the effectiveness of Medically Supervised Injection Centres. Studies have been conducted in Australia, Canada, Denmark, and Spain. However, there have been few attempts to conduct a quantitative analysis of these studies to determine the impact of the body of research as a whole.”

The researchers went through 40 studies to aggregate and analyze, but determined that only eight were rigorous enough to meet their standards to include in the meta-study.

Dr. Caleb Banta-Green at the University of Washington has studied the impact of opioids for nearly 20 years. His reaction to the study?

“That’s surprising. And then you dig into it and realize they’re doing a different type of study. And they’re looking at eight studies of four locations, even though there are more than 100 locations around the world,” Banta-Green said.

“I think that the main finding of the study is not something we can generalize and say hey, this little study found this, so safe consumption sites don’t work. This really does not show that,” Banta-Green said.

He also said increasing cases of fentanyl showing up in heroin- making it more deadly- might have an impact, offsetting benefits of safe consumption sites.

Seattle wants to set up what the city calls a “fixed mobile” safe injection site. In a vehicle that’s similar, but larger than its mobile medical van.

Supporters of safe injection sites have long said they’re necessary to save lives.

“We’re trying to stop deaths here and we need to do so with urgency,” said Seattle City Council member Teresa Mosqueda during a committee meeting in June.

Last year, 379 people in King County died from drug overdose -the highest ever.

Banta-Green admits the impact of safe-injection sites on lives saved might be small -and tough to ever see in studies.

He part of that reason is because the people who are worst off are also the most difficult to track and trace for research. He said the people who are well enough to participate in a study and keep in contact with researchers are not representative of the population that’s suffering.

“It (safe injection sites) may not help with mortality rates. I suspect it does but its small. About 1 to 2 percent of opiate injectors die every year. So you have to be studying thousands of people to see an effect of that,” Banta-Green said.

“If it doesn’t have any impact on mortality, what makes it better than shooting up on the street?” KIRO7’s Deedee Sun asked.

“You’re in a stainless steel, sterilized environment. People aren’t going to be getting or transmitting diseases, they’re not going to be getting hepatitis or HIV. And if they do OD, they can be given oxygen or Narcan and be kept alive,” Banta-Green said.

And he says it’s a starting point to at least reach a group of people, previously unreachable by those who want to help.

“What we’re hoping for over time is they’ll get some stability, they’ll gain some trust for staff who work there, and they’ll be willing to take some steps to get it under control,” Banta-Green said.

Even the researchers of the study agree their work doesn’t mean safe-injection sites don’t work.

The conclusion says, “While the effectiveness of the early versions of MSICs remains uncertain, this should not rule out continuing to test and develop MSICs in locations where public injecting and drug-related harms are a major problem.”

In June, KIRO7’s Deedee Sun was told by Meg Olberding with Seattle’s Human Services Department that the city would be narrowing down the fixed site locations within the next “two months,” and start community outreach and engagement in July.

On Aug. 23, Olberding referred requests for an update to Mayor Jenny Durkan’s office.

Spokeswoman Kamaria Hightower said over the phone that community outreach has been done and no locations have been narrowed down. The city said there was no progress since June, no timeline, and would need to look into why there was progress.

Hightower said their community outreach would absolutely be done before any decision on a “fixed mobile” safe injection site.